巨桉扩展蛋白EgrEXPA8和EgrEXPA10基因的克隆和表达特性分析

Cloning and Expression Analysis of EgrEXPA8 and EgrEXPA10 Genes in Eucalyptus grandis

摘要:

为探讨扩展蛋白在桉树生长发育中的作用，以在桉树初生生长到次生生长转换转录组测序中筛选出的差异表达基因EgrEXPA8和EgrEXPA10为基础，从巨桉(Eucalyptus grandis)中克隆了2个扩展蛋白基因EgrEXPA8和EgrEXPA10，分别编码249和244个氨基酸，属于亲水蛋白，但EgrEXPA8稳定性高于EgrEXPA10。qRT-PCR分析表明，EgrEXPA8和EgrEXPA10基因均在幼叶和茎尖组织中表达量较高，在木质部和韧皮部表达量较低；且在茎顶端初生生长阶段表达量较高，而在下部次生生长节间表达量较低，可能其主要参与巨桉的初生生长或者负调控次生生长；另外在盐胁迫、茉莉酸甲酯处理下其均被抑制表达；而在水杨酸、缺硼、缺磷处理下均上调表达。这说明EgrEXPA8和EgrEXPA10在巨桉响应逆境胁迫时起到重要作用，且呈现出相似的调控方式。

Abstract:

To elucidate the function in growth and development of expansins in Eucalyptus, two expansin genes EgrEXPA8 and EgrEXPA10 were cloned based on differential expression genes in the transcriptome of transition from primary growth to secondary growth of E. grandis. EgrEXPA8 and EgrEXPA10 encoded 249 and 244 amino acids, respectively. EgrEXPA8 and EgrEXPA10 were hydrophilic proteins. However, the stability of EgrEXPA8 was higher than that of EgrEXPA10. qRT-PCR analysis showed that the expression of EgrEXPA8 and EgrEXPA10 were high in young leaves and stem apex, and low in xylem and phloem. The expression of them was high in stem apex at primary growth stage, and low in internode at secondary growth stage, indicating that the two genes might be mainly involved in primary growth or negative regulation of secondary growth in E. grandis. The expressions of EgrEXPA8 and EgrEXPA10 were inhibited under salt stress and methyl jasmonate treatment, but significantly up-regulated treated with salicylic acid, under boron and phosphorus deficiency. Therefore, it was suggested that EgrEXPA8 and EgrEXPA10 genes in E. grandis would play an important role in response to stress.